Immediate payment has always, theoretically, been a seller choice. Most people would pay immediately for BINs, but it's certainly not a given.

I don't have it and never had. Luckily eBay has yet to impose it on me, which seems to be the case for others, but it is not an official policy.

It you want to ensure immediate payment, and have no interest in combining postage or offering volume discounts, set it yourself. It's your account and your responsibility, not eBay's, to manage it the way YOU want.